1. Field of the Invention
This invention relates to a surgical instrument and more particularly to an instrument with the capability for continuous irrigation and evacuation of fluid into and out from a body cavity of a patient during Laparoscopic or Endoscopic surgical procedures, and for the simultaneous measurement of tissue impedance and the ablation of tissue with fixed or retractable electrodes using R.F. energy.
2. Brief Description of the Prior Art
Laparoscopic/endoscopic surgical procedure allows a surgeon to see inside the body cavity of a patient without the necessity of large incisions. This reduces the chances of infection and other complications related to large incisions. The endoscope further allows the surgeon to manipulate microsurgical instruments without impeding the surgeon's view of the area under consideration.
During these surgical procedures it is desirable for as few lines as possible to enter the body of the patient. This reduces the size of the incision the surgeon needs to make. It follows from this that the greater the number of functions provided by a single instrument or the greater the number of instruments able to be passed through a single line entering the patient's body, the better.
Furthermore, in certain procedures it may be desirable to irrigate the area under consideration. This in turn necessitates the evacuation of the irrigation fluid or, when bleeding has occurred, the blood or smoke or tissue residue generated by the surgical procedure.
From what has been said above it should be apparent that it is preferable for both irrigation and evacuation to be conducted along a single conduit which, also, acts as an access line for surgical instruments.
A typical device which is used in endoscopic procedures is an electrosurgical probe. Typically such a probe will comprise a radio frequency (i.e. R.F.) energy conductive tube covered with a dielectric material such as polyolefin or Teflon. At one end, for convenience called the operational end, each probe could have any one of a number of functionally shaped monopolar or bipolar electrodes. In addition a probe could have its end formed specifically for irrigation and/or evacuation.
Monopolar and bipolar electrode probes are known in the prior art. Monopolar electrode probes include a single active electrode which is surgically introduced into a body cavity and engagable with and insertable into a tissue portion of the cavity. A passive electrode is attached to the outer body surface of the patient, e.g. typically a conducting plate is adhesively attached to the patient's leg. The body of the patient serves to complete the electrical circuit. Tissue ablation and coagulation is achieved by introducing sufficient power into the active electrode. Bipolar electrode probes include both active and passive electrodes which are similarly introduced together into the body cavity and are spaced apart from each other by a predetermined distance. Each electrode is engageable with and insertable into the tissue portion. Thus, the electrical circuit is completed by the body tissue disposed between the active and the passive electrodes and only the body tissue disposed between the two electrodes get coagulated.
Furthermore, any valves controlling the evacuation and irrigation procedures should be constructed so as to minimize the possibility of the valve malfunctions if, for example, any tissue or blood coagulates around their moving parts. Similarly if any of the instrumentation is to be reusable, such instrumentation, including the valves, should be capable of being efficiently cleaned by, for example, flushing.
U.S. Pat. No. 4,668,215 (Allgood) discloses a valve for switching between an evacuation and an irrigation conduit and allowing both such evacuation and irrigation to be done via a single line entering the patient. The mechanism for switching between the irrigation, evacuation and closed configurations is by means of a L-valve or T-valve. This patent, in another embodiment thereof, further provides for a piston valve for making an on-off connection between an evacuation port and the line leading into the patient.
The L- and T-valves have the disadvantage that they must be manipulated by rotation by the surgeon, usually using his/her free hand. The piston valve disclosed in this patent has the disadvantage that it has many areas where blood and tissue accumulation and coagulation can occur which may result in the malfunctioning of the valve. In addition, the piston valve has numerous "dead" areas where fluid flow would not occur. This precludes the device from being effectively cleaned by commonly used flushing techniques. Finally, the Allgood patent does not disclose a single body for housing an evacuation/irrigation control valve together with a housing for laparoscopic and microsurgical instrumentation.
A surgical valve that the applicant is aware of is the piston valve illustrated in FIG. 1 of the accompanying drawings.
In this valve a piston 10 is located within a cylinder 11. The piston 10 can be moved along the bore of the cylinder 11 by means of a plunger 12, from a closed position (as shown) to an open position in which a conduit 13 is aligned with an access port 14. This allows fluid flow along a path to or from access port 14, via conduit 13 and space 16 from or to a further port 15. Upon release of the plunger 12 the piston 10 returns to its closed position under action of a spring 17.
This valve, although easy to use, has the disadvantage that blood and tissue accumulation occurs in space 16 and clogs both the space and the spring 17. This may result in undesirable over-evacuation or irrigation of the patient during surgical procedures.